The futon sofa bed has grown from a small and simply made item to a larger market product with a greater breadth of styling, function and appeal. Along with its growth has been an increased need for better quality styling and finishes as well as a need for enhanced user friendliness in several aspects of the product. Among these aspects are:
1. Improved ease of conversion from a sofa (seating) position to the bed position and back to the sofa position; and
2. Easier user-assembly of the frame.
The following addresses these two aspects including discussion of problems with the prior art.
Aspect 1: Improved Ease of Conversion and a Discussion of Front Loaders (Prior Art)
The futon sofa bed is a convertible product, converting from a bed position to a sofa position and back again. Accordingly, the futon sofa bed requires moving and mechanical parts to achieve these conversions.
One class of conventional futon frames required the user, when converting, to insert and remove wooden pegs to hold the frame in the seating and bed positions. A later developed class of conventional futon frames permits the back-deck frame to slide using plastic pegs (runners) which run in grooves in the arm-panels, allowing easier movement between the positions of seating and bed. This later developed class is one of the most popular in use today.
However, both classes of conventional futon frames require some strength and care when converting, and can be awkward for the user as example, in the later developed class, when converting from seating to the bed position, care is needed when pulling the seat forward (the primary step in conversion) so as not to let the back-deck come down quickly and slam hard into its horizontal (bed) position, under its own weight. When converting back from the bed to seating positions, the user must first stand at the front of the seat-deck to pull the seat out of its locked position and then move to the back of the frame to lift the back-deck up into a near seating position. Finally the user must return to the front to push the seat deeper into its final seating position.
From its earliest engineering and styling, the futon sofa bed has striven to find simple and economical forms of engineering to achieve these conversions. Simplicity of engineering, and value for money are among the futon sofa bed's strongest defining features.
Unfortunately, the simplicity in the futon sofa bed's engineering designs has not always made the futon sofa bed easy to use (nor has it kept it free from breakage, due to the stresses it endures during use).
To make the product easier to use a number of improvements in the futon sofa bed's converting mechanisms have been made in recent years.
These converting mechanisms are commonly known as front converting system, ‘front loader’, ‘kicker’, or ‘convert-with-ease’ to name a few. All these solutions use a system of two points on the seat or back-deck forming a ‘lock’ onto the other platform (seat or back-deck) so as to lock-and-lever up or down the back-deck into the desired position by moving (levering) the seat-deck, thereby operating only from the front.
While these solutions allow the user to convert from the front with more ease and control, they have a number of flaws and have not become widely used or accepted. Among these flaws are the following:
a. Breakage Due to Metal Pin
The use of small metal pins (for example ⅜″ diam.) in wood slots (grooves), which are used both as pivot and ‘locking’ points, which can cause damage, and often causes breakage to frame components when used. Great stress is put on the contact point between the metal pin and the wall of the wood slot. Because the length of the wood slot runs parallel to the wood grain, the stress often splits the wood.
b. Damage To Wood Slot From Metal Pin
The same metal pins, mentioned above, can leave indentations in the wooden wall of the slot when used under stress. These indentations make smooth movement in the slots increasingly difficult over time.
c. Early Release
When converting from the seating to the bed position, it is easy for the user to pull too hard or too gently forward on the seat-deck. This can cause the ‘lock’ points to miss and not lock and release too early, causing the back-deck to fall down hard.
d. Jamming
When converting from the sofa position to the bed position, it is easy for the user to pull unevenly forward on the seat-deck. This can cause the ‘lock’ points to release on one side only and cause the frame to jam as one side releases and the other remains locked. This can cause damage or breakage to the frame.
e. Shortening of the Seat-Deck in Seating Position
Because the metal pins are in a fixed position on the back-deck and the slots in the seat-deck slide over them, the nature of this design requires that the seat-deck move deeper in (in towards, and under, the back-deck) when pushed into the final seating position. The sliding of the seat-deck towards and under the back-deck results in the shortening of the seat-deck in the final seating position by about 1½″. This is noticeable to the sitter (especially taller ones). It is difficult to try to correct this problem by re-positioning the slot in the seat-deck due to the joining of other frame components in that same area. Alternately, lengthening the seat-deck by 1½″ to compensate for the shortened position makes the platform too wide in the bed position.
f. Stress to the Inside Back-Deck Long-Rail
Many of these conventional solutions require the inside long-rail of the back-deck to be used as one of the two locking points (catching the seat-deck frame under it as the seat-deck slides under the long-rail in the final seating position). This causes stress and can cause breakage to the long-rail where it joins to the other back-deck frame components.
Additionally, in recent years the futon mattresses used on the frames have become increasingly heavier. The increasing weight of the mattress amplifies the problems listed above.
As a result of the problems listed above the various front converting systems have not been widely accepted in the futon industry. Generally, front converting systems have a reputation for difficulty of use and ease of breakage.
As described above, these front converting improvements have generally employed slots and pins, cut or set into the wooden components. These systems have seen substantial breakage during use due to both the designs of the mechanisms, and due to the materials used. Metal pins forced against wooden grooves and slots also tend to stress and split the wooden components.
Attempts have been made to overcome this as in (for example U.S. Pat. No. 5,083,333 to Newton) by using a metal plate stamped with slots and notches to take the force exerted by the metal pins, and thereby relieve the stress on the wooden components.
Although the use of a metal plate can reduce breakage, it has never found broad usage in the futon sofa bed industry partly due to the metal against metal sound/feel effects and other negative metal qualities. Further, the rigid nature of metal has limited potentially desirable features and design improvements to the futon sofa bed conversion mechanism.
Aspect 2: Easier User Assembly of the Frame Parts
The following is a discussion of the three main assembly difficulties:
1. attaching stretchers to arms;
2. attaching the seat-deck to the back-deck; and
3. fitting of seat and back-decks between arms.
a. Attaching Stretchers to Arms
For the majority of futon sofa beds in the market, the standard system of assembly of the stretcher rails (support beams spanning and connecting the arm panels at each end) to the arm panels is by means of threaded bolts which attach and thread into barrel nuts. The threaded bolts are inserted from outside the arm panels, through holes in the arm panels and then into holes drilled in the ends of the stretchers—and then connecting and threading into barrel nuts.
Conventional barrel nuts generally provide slots in the top end of the nut so that the user can use a screwdriver to assist with positioning of the nut within the hole. However, a screwdriver has limited control over the positioning of the nut as it can push the nut deeper into the hole but it can not pull it back out again. A screwdriver can rotate the nut but it can not necessarily rotate the nut at the correct depth inside the hole for correct alignment with the bolt. This is a great drawback of the common barrel nut and causes frustration to the assembler/user.
b. Attaching the Seat-Deck to the Back-Deck
Conventional futon sofa beds utilize a pivot pin to make the connection between the seat-deck and the back-deck and this pin must be fit through a hole in the seat side frame, and align with a hole in the back side frame. The fitting of these pins is awkward and alignment of these holes can be difficult. When fitting the pins into the holes, the back-deck is generally set into it's seating (upright) position between the arm panels and then the seat deck is held manually in place while the pivot pins are inserted.
To add further to this difficult assembly, on occasion, when the design and style of the arm panels are such that they do not provide open access from the outside to these pivot pin holes, and are designed with closed panels that are low enough on the arm to prevent access, the user must assemble the seat-deck to the back-deck completely first, using the pivot pins, before fitting the decks into their position between the arm panels. This requires lifting both decks together as one assembled unit, and with great strength, manipulating the two heavy decks into position.
c. Fitting of Seat and Back-Decks Between Arms
As a converting mechanism the conventional groove and runner system works very well. However, again there are problems in the frame assembly using this system.
The problem comes in when assembling the seat and back decks into the grooves in the arm panels. This assembly requires great care to be taken in the following steps:
1) Assemble Arms to Stretchers
The user starts by assembling the arm panels to the stretcher rails to form the basic framework of the futon frame. The stretcher rails are generally bolted to the arm panels.
2) Leave the Bolts Loose
The bolts must not be tightened at this early assembly stage. The assembler must leave each bolt a few turns loose to ensure a clearance is given when fitting runners into grooves. Although assembly instructions tell the assembler to leave the bolts loose, it is difficult to explain exactly how loose. Additionally, if the bolts are too loose the bolts holding the arms and stretcher may not be securely threaded to hold properly.
3) Fitting the Runners into the Grooves
When the stretchers and arms are attached to each other and the connection between them left loose, the assembler needs to lift the back-deck into place. To do this the assembler must hold the back-deck over the frame and fit the runners at one end of the back-deck into the grooves of the arm panel. Once the runners are in place the assembler must lower the other end of the back-deck carefully, down past the edge of the arm rest of the arm panel, and manipulate the runners at that end into the grooves of the arm panel at that end. This is always a difficult step and can cause damage to finished surfaces of the arm panels. Generally, two people are needed.
Additionally, with some arm panel designs, the seat-deck and the back-deck need to be joined together before fitting the back-deck runners into the grooves (this is true with arm designs that have panels low to the floor not allowing access to the connection point from the outside, thereby requiring the assembler to join the decks before they are fit into the arm panels). This is a dangerous procedure in particular for the exposed finished surfaces and causes damage to the exposed parts.